The purpose of this CORE is to provide the animal resources for the research proposed in the 4 projects. In AIM 1,we will produce new crosses of transgenic and knock out strains and screen the various crosses we will use. We will cross transgenic or knock out mice onto new backgrounds, new MHC, cross to strains carrying genetic markers, cross transgenics to gene knock out strains and make and test various F1 progeny. We will continue to breed and screen a number of unique mouse strains that we have already produced that will be needed in the four Projects in this program. The centralized production of specialized mice will result in increased efficiency and allow for sound quality control. In AIM 2 we will develop and test the biological function of additional strains based on the cytokine reporter mice, the 4get (IL-4 GFP enhanced transcript) mice and YETI (yellow enhanced transcript for IFN-gamma) that we have already made. These mice provide a valuable reagent for assessing immunity in vivo and both strains will be crossed to a variety of genetic backgrounds and will be tested for their performance compared with cells from wild type mice under an number of in vitro and vivo conditions. The activities of the CORE will ensure the supply of crucial mouse strains at a reasonable cost to all four projects. Equipment will be purchased to provide the appropriate housing and support safe health and handling of mice within the Institute's Experimental Animal Maintenance Facility (EAM). Renovations will be carried out in the EAM to provide adequate ABL 3 space for the studies with tuberculosis-infected mice and ABL 2 space for studies with flu-infected mice.